Motor control system providing single output signal and high number of speed settings

ABSTRACT

A motor control system providing at least seventeen speed settings using industry standard control signals and an industry standard five pin speed connector. One speed monitoring pin transmits an output signal for monitoring the speed of the motor, and four speed setting pins receive input signals for setting the speed. One of the speed setting pins receives and decodes two binary states and two frequency states, thereby providing a total of thirty-two speed settings. A non-regulated isolated winding is added to an internal transformer to provide an internal isolated flyback power supply for the motor, thereby liberating a pin on the industry standard five pin speed connector to provide the fourth speed setting input pin. Transmission circuitry is associated with the speed monitoring pin, and the non-regulated isolated winding is used to provide a direct current bias to the transmission circuitry.

RELATED APPLICATIONS

The present U.S. non-provisional patent application is related to andclaims priority of an earlier-filed provisional patent applicationtitled “Motor Control System Providing Single Output Signal and HighNumber of Speed Settings,” filed May 13, 2020, Ser. No. 63/024,009. Theentire content of the identified earlier-filed application isincorporated by reference as if fully set forth herein.

FIELD

The present invention relates to electric motors and motor controllers,and more particularly, embodiments concern a motor control system withat least seventeen motor speed settings using industry standard controlsignals and an industry standard five pin speed connector.

BACKGROUND

Manufacturers of heating, ventilation, and air conditioning (HVAC)systems desire to increase the number of discrete speed settingsavailable on blower motors from the five settings currently available.Additional speed settings are desirable in order to increase comfort forend-users, allow installers to better control torque for improvedairflow, and allow manufacturers to reduce the number of differentproducts they provide and support. However, the ability to acceptmultiple speed inputs is limited by the number of input and output pinson the industry standard five pin speed connector. Currently, only threeof the five pins are available for speed inputs, which limits themaximum number of speed settings to eight.

This background discussion is intended to provide information related tothe present invention which is not necessarily prior art.

SUMMARY

Embodiments overcome the above-described and other limitations in theprior art by providing a motor control system with at least seventeendiscrete motor speed settings using industry standard control signalsand an industry standard five pin speed connector. Embodimentsadvantageously increase comfort for end-users, allow installers tobetter control torque for improved airflow, and allow manufacturers toreduce the number of different products they provide and support.

In one embodiment, a control system is provided for controllingoperation of an electric motor. The control system may be configured toprovide at least seventeen speed settings for a speed of the electricmotor, wherein the at least seventeen speed settings are achieved usinga standard five pin speed connector including first, second, third,fourth, and fifth pins to communicate via electrical signals with theelectric motor. The control system may include one speed monitoringoutput pin and four speed setting input pins. The speed monitoringoutput pin of the five pins on the standard five pin speed connector maybe configured to transmit an output signal for monitoring the speed ofthe electric motor. The first, second, third, and fourth speed settinginput pins of the five pins on the standard five speed pin connector maybe configured to receive input signals for setting the speed of theelectric motor, wherein at least one of the four speed setting inputpins receives and decodes two binary states and two frequency states.

Various implementations of the foregoing embodiment may include any oneor more of the following additional features. The electric motor may bea blower motor in a heating, ventilation, and air conditioning system.The two frequency states are sixty Hertz and one hundred twenty Hertz.In a first implementation, within the standard five pin speed connectora transmit circuitry on the fourth pin may be eliminated to make thefourth pin an open collector, and a direct current bias network on thefifth pin is eliminated, which liberates the fifth pin to be the fourthspeed setting input pin. In a second implementation, the control systemfurther includes a standard four pin power connector including areference voltage pin, and within the standard five pin speed connectorall optocouplers may be eliminated except for a first optocouplerassociated with a receiving circuit and a second optocoupler associatedwith a transmitting circuit, a power supply may be replaced with anisolated flyback power supply, which liberates the reference voltage pinto be the fourth speed setting input pin. In a third implementation, anon-regulated isolated winding may be added to a main transformer in theelectric motor to provide an isolated power supply, the non-regulatedisolated winding may be used to provide a direct current bias on thereference voltage pin for a transmission circuit associated with thefirst speed monitoring output pin for transmitting an output signal formonitoring the speed of the electric motor, which liberates the fifthpin to be the fourth speed setting input pin.

This summary is not intended to identify essential features of thepresent invention, and is not intended to be used to limit the scope ofthe claims. These and other aspects of the present invention aredescribed below in greater detail.

DRAWINGS

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a depiction of an embodiment of a motor control system with atleast seventeen motor speed settings using industry standard controlsignals and an industry standard five pin speed connector, wherein themotor control system is shown operationally coupled with an exampleelectric motor for driving a load such as a blower in an HVAC system;

FIG. 2 is a diagram of power connector and speed connector components ofthe motor control system of FIG. 1, showing input and output pins forthe connectors;

FIG. 3 is a high level circuit diagram of a first implementation of themotor control system of FIG. 1;

FIG. 4 is a high level circuit diagram of a second implementation of themotor control system of FIG. 1; and

FIG. 5 is a high level circuit diagram of a third implementation of themotor control system of FIG. 1.

The figures are not intended to limit the present invention to thespecific embodiments they depict. The drawings are not necessarily toscale.

DETAILED DESCRIPTION

The following detailed description of embodiments of the inventionreferences the accompanying figures. The embodiments are intended todescribe aspects of the invention in sufficient detail to enable thosewith ordinary skill in the art to practice the invention. Otherembodiments may be utilized and changes may be made without departingfrom the scope of the claims. The following description is, therefore,not limiting. The scope of the present invention is defined only by theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

In this description, references to “one embodiment,” “an embodiment,” or“embodiments” mean that the feature or features referred to are includedin at least one embodiment of the invention. Separate references to “oneembodiment,” “an embodiment,” or “embodiments” in this description donot necessarily refer to the same embodiment and are not mutuallyexclusive unless so stated. Specifically, a feature, component, action,step, etc. described in one embodiment may also be included in otherembodiments, but is not necessarily included. Thus, particularimplementations of the present invention can include a variety ofcombinations and/or integrations of the embodiments described herein.

Broadly, embodiments provide a motor control system with at leastseventeen motor speed settings using industry standard control signalsand an industry standard five pin speed connector to communicate viaelectricals signals with an electric motor. Embodiments advantageouslyincrease comfort for end-users, allow installers to better controltorque for improved airflow, and allow manufacturers to reduce thenumber of different products they provide and support. Potentialapplications for the control system include controlling blower motorsfor driving blowers HVAC units.

Referring to FIG. 1, an example HVAC system 20 may include an electricmotor 22 including a shaft 26 for driving a load such as a blowercomponent of the system 20. The motor 22 may be coupled with a motorcontrol system 24 for controlling operation of the motor 22. Referringalso to FIG. 2, the motor control system 24 may include two connectors,a power connector 28 and a speed connector 30. These may be industrystandard connectors (i.e., connectors of standard designs that arecurrently widely used in the industry and understood by those withordinary skill in the relevant art), such as the positive lock HVACmotor connectors available from, e.g., TE Connectivity Ltd. (formerlyTyco Electronics). The power connector 28 may have four pins, or “taps,”for line (L), ground (G), and neutral (N) connections for one hundredtwenty/two hundred forty VAC input power, and reference voltage orcommon (C). The speed connector 30 may have five pins, PIN1, PIN2, PIN3,PIN4, and PIN5. PIN1 may be a receive (Rx) pin for receiving signals,and PIN4 may be a transmit (Tx) pin for sending signals. In the priorart, two of the five pins are used to monitor the speed of the motor 22and three are used to set the speed of the motor 22. Three speed settinginputs allow for eight binary states and therefore a maximum of eightspeed settings.

Embodiments of the present invention liberate one of the two speedmonitoring pins or the reference voltage pin of the speed connector 30for use as a fourth speed setting pin, leaving only one pin formonitoring speed. Four speed setting inputs allow for sixteen binarystates and therefore sixteen speed settings. Additionally, embodimentsprovide two binary states and two frequency states on at least one ofthe speed setting pins to allow for a total of thirty-two states andtherefore, potentially, thirty-two speed settings (i.e., at leastseventeen motor speed settings). In one implementation, the twofrequency states may be sixty Hz (one-half wave rectified) and onehundred twenty Hz (full-wave rectified), while in other implementationsother frequencies may be used. Thus, at least one of the four speed pinsmay have four possible states: on, off, sixty Hz, and one hundred twentyHz.

In one example implementation, the speed connector 30 of the motorcontrol system 24 may provide the four speed setting pins configured toreceive DC or logic pulse input signals, with a logic “high” voltage ofeighteen V minimum, twenty-four V nominal, and thirty V maximum, a logic“low” voltage of one V or less, and a typical current of between five mAand twenty mA. At least one of the speed setting pins may be furtherconfigured to also receive an additional AC input signal which may besixty Hz or one hundred twenty Hertz, but otherwise have the sameelectrical characteristics as the DC input signals. The speed connector30 may further provide one speed monitoring pin configured as an opencollector output, with a maximum voltage of thirty V, a maximum sinkcurrent of twenty mA, and a logic “low” voltage of one point two V orless.

In a first implementation, shown in FIG. 3, a fourth pin may beliberated for use in setting the speed of the motor 22 as follows.Broadly, within the standard five pin speed connector a transmitcircuitry on the fourth pin may be eliminated to make the fourth pin anopen collector, and a direct current bias network on the fifth pin maybe eliminated, which liberates the fifth pin to be the fourth speedsetting input pin. In more detail, in the standard speed connector 30,PIN4 has an optocoupler, and PIN5 connects to a user-supplied DC biasnetwork. In this first implementation, the transmit circuitry of PIN4may be removed to make it an open collector, and the DC bias network maybe removed, thereby liberating PIN5 for use as the fourth speed settinginput pin. Additional protection circuitry may be added as desired orneeded.

In a second implementation, shown in FIG. 4, the fourth pin may beliberated for use in setting the speed of the motor 22 as follows. Asdiscussed, the control system further includes a standard four pin powerconnector including a reference voltage pin. Broadly, within thestandard five pin speed connector all optocouplers may be eliminatedexcept for a first optocoupler associated with a receiving circuit and asecond optocoupler associated with a transmitting circuit, a powersupply may be replaced with an isolated flyback power supply, whichliberates the reference voltage pin to be the fourth speed setting inputpin. In more detail, an “on board” modular connector may beincorporated. All but two optocouplers may be removed, with one retainedfor receiving and one retained for transmitting. The power supply may bechanged to an isolated flyback power supply used on the modularconnector. A small microprocessor having more input pins may be added,and a three and three-tenths V switching power supply or three andthree-tenths V linear regulator may be added to provide power to themicroprocessor. The tap inputs may be modified to be three andthree-tenths V compliant. By removing all but two of the optocouplers,this solution allows for thirty-two speed settings while keeping otheraspects of the system, such as the negative temperature coefficient(NTC) circuit and the reference sensing circuit, the same.

In a third implementation, shown in FIG. 5, the fourth pin may beliberated for use in setting the speed of the motor 22 as follows.Broadly, a non-regulated isolated winding may be added to a maintransformer in the electric motor to provide an isolated power supply,the non-regulated isolated winding may be used to provide a directcurrent bias on the reference voltage pin for a transmission circuitassociated with the first speed monitoring output pin for transmittingan output signal for monitoring the speed of the electric motor, whichliberates the fifth pin to be the fourth speed setting input pin. Inmore detail, an isolated winding 32 may be added to the main transformer34 in the motor 22, which provides an isolated power supply. In moredetail, the conventional buck configuration may be replaced with anisolated flyback power supply to provide the isolated winding 32. Thenon-regulated isolated winding output voltage may be used to provide aDC bias on a DC bias line 36 for the Tx circuitry. The transformer 34may be modified to add more voltage to the non-regulated output winding32. In the prior art, this power supply is provided by the external HVACsystem 20 and occupies one of the available pins on the systemconnector. Thus, this solution liberates one pin, and provides four pinsfor receiving and decoding the discrete speed inputs and one pin forproviding motor speed feedback and one pin as a signal reference.

It will be understood that the solution of reducing the number of outputpins to increase the number of input pins may have applications otherthan increasing the number of speed settings, and may therefore beseparate and distinct from the solution of using more than two states onan input pin to achieve a higher number of speed settings. Similarly, itwill be understood that the solution of using more than two states on aninput pin may be employed without reducing the number of output pins,and may therefore be separate and distinct from the solution of reducingthe number of output pins to increase the number of input pins.

Thus, in one embodiment, the control system may include one output pinon the industry standard five pin speed connector configured to transmitan output signal for monitoring the speed of the electric motor, andfour input pins on the industry standard five pin speed connector,wherein at least some but not necessarily all of the four input pins areconfigured to receive input signals for setting the speed of theelectric motor. In another embodiment, the control system may include atleast one output pin on the industry standard five pin speed connectorconfigured to transmit an output signal, and at least one input pin onthe industry standard five pin speed connector configured to receive aninput signal, wherein at least one of the at least one input pin isconfigured to receive and decode two binary states and two frequencystates.

Although the invention has been described with reference to the one ormore embodiments illustrated in the figures, it is understood thatequivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described one or more embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A control system for controlling operation of anelectric motor, the control system providing at least seventeen speedsettings for a speed of the electric motor, wherein the at leastseventeen speed settings are achieved using a standard five pin speedconnector including first, second, third, fourth, and fifth pins tocommunicate via electrical signals with the electric motor, the controlsystem comprising: one speed monitoring output pin of the five pins onthe standard five pin speed connector transmitting an output signal formonitoring the speed of the electric motor; and first, second, third,and fourth speed setting input pins of the five pins on the standardfive speed pin connector receiving input signals for setting the speedof the electric motor, wherein at least one of the four speed settinginput pins receives and decodes two binary states and two frequencystates.
 2. The control system of claim 1, wherein the electric motor isa blower motor in a heating, ventilation, and air conditioning system.3. The control system of claim 1, wherein the two frequency states aresixty Hertz and one hundred twenty Hertz.
 4. The control system of claim1, wherein within the standard five pin speed connector a transmitcircuitry on the fourth pin is eliminated to make the fourth pin an opencollector, and a direct current bias network on the fifth pin iseliminated, and the fifth pin is the fourth speed setting input pin. 5.The control system of claim 1, the control system further including astandard four pin power connector including a reference voltage pin,wherein within the standard five pin speed connector all optocouplersare eliminated except for a first optocoupler associated with areceiving circuit and a second optocoupler associated with atransmitting circuit, a power supply is replaced with an isolatedflyback power supply, and the reference voltage pin is the fourth speedsetting input pin.
 6. The control system of claim 1, wherein anon-regulated isolated winding is added to a main transformer in theelectric motor to provide an isolated power supply, the non-regulatedisolated winding is used to provide a direct current bias on thereference voltage pin for a transmission circuit associated with thefirst speed monitoring output pin for transmitting an output signal formonitoring the speed of the electric motor, and the fifth pin is thefourth speed setting input pin.
 7. A control system for controllingoperation of an electric motor which is a blower motor in a heating,ventilation, and air conditioning system, the control system configuredto provide at least seventeen speed settings for a speed of the electricmotor, wherein the at least seventeen speed settings are achieved usinga standard five pin speed connector including first, second, third,fourth, and fifth pins to communicate via electrical signals with theelectric motor, the control system comprising: one speed monitoringoutput pin of the five pins on the standard five pin speed connectortransmitting an output signal for monitoring the speed of the electricmotor; and first, second, third, and fourth speed setting input pins ofthe five pins on the standard five speed pin connector receiving inputsignals for setting the speed of the electric motor, wherein at leastone of the four speed setting input pins receives and decodes two binarystates and two frequency states, and the two frequency states are sixtyHertz and one hundred twenty Hertz, and wherein a transmit circuitry onthe fourth pin is eliminated to make the fourth pin an open collector,and a direct current bias network on the fifth pin is eliminated, andthe fifth pin is the fourth speed setting input pin.
 8. A control systemfor controlling operation of an electric motor which is a blower motorin a heating, ventilation, and air conditioning system, the controlsystem configured to provide at least seventeen speed settings for aspeed of the electric motor, wherein the at least seventeen speedsettings are achieved using a standard five pin speed connectorincluding first, second, third, fourth, and fifth pins and a standardfour pin power connector including a reference voltage pin tocommunicate via electrical signals with the electric motor, the controlsystem comprising: one speed monitoring output pin of the five pins onthe standard five pin speed connector transmitting an output signal formonitoring the speed of the electric motor; and first, second, third,and fourth speed setting input pins of the five pins on the standardfive speed pin connector receiving input signals for setting the speedof the electric motor, wherein at least one of the four speed settinginput pins receives and decodes two binary states and two frequencystates, and the two frequency states are sixty Hertz and one hundredtwenty Hertz, and wherein within the standard five pin speed connectorall optocouplers are eliminated except for a first optocouplerassociated with a receiving circuit and a second optocoupler associatedwith a transmitting circuit, a power supply is replaced with an isolatedflyback power supply, and the reference voltage pin is the fourth speedsetting input pin.